JP4176789B2 - Exhaust gas receiver for large two-cycle diesel engines - Google Patents

Description

  The present invention relates to an exhaust gas receiver for a large two-cycle diesel engine, and more particularly to an exhaust gas receiver for a multi-cylinder in-line engine.

  The exhaust receiver of a large two-cycle diesel engine is a component that receives high loads and receives high-temperature (450 ° C.) exhaust gas from individual cylinders at a pressure of about 4 bar. In addition to thermal and pressure loads, engine vibrations cause the structure to vibrate, thereby further increasing the mechanical load on the exhaust gas receiver. Due to the large size of the exhaust gas receiver (which may exceed 10 m in length) and the high operating temperature, the exhaust gas receiver has a significant thermal expansion, and larger engines are subject to dimensional changes caused by thermal expansion. For absorption, it has an exhaust gas receiver divided into two or more housing parts separated by bellows. The completed exhaust gas receiver and its accessories are covered with a thick layer of insulation so that the temperature of the external surface of the exhaust gas receiver is substantially lower than the temperature of the exhaust gas inside the exhaust gas receiver. According to safety regulations, the temperature of the external surface of the exhaust gas receiver should not be so high that any exposed engine parts ignite oils that could inadvertently come into contact with engine fuel or engine parts. It is calculated | required to set it as 220 degrees C or less. In practice, the external surface of the exhaust gas receiver is sufficiently insulated so that its surface temperature is kept below 150 ° C.

  From a cost standpoint, it is most economical to provide a large two-cycle diesel engine with only one turbocharger at one of the longitudinal ends of the engine, but the cylinder at the opposite end of the engine As a result, the distance of the exhaust gas transported from the air becomes long, causing problems. In practice, large two-cycle diesel engines are manufactured exclusively as in-line engines. Generally, the number of cylinders varies from 5 to 14, and an engine with a large number of cylinders naturally becomes longer. In general, a single turbocharger is mounted at the end of a large two-cycle diesel engine. At the longitudinal end of the exhaust gas receiver closest to the server charger is provided an exhaust port that is substantially directly connected to the intake port of the turbocharger. Therefore, the exhaust gas from the cylinder located at a location away from the turbocharger needs to travel a distance along the entire length of the engine. The distance that the exhaust gas must travel from the cylinder closest to the turbocharger is very short. The distance between the nearest cylinder and the farthest cylinder can be 10 m or more.

  In addition, exhaust pressure pulsations cause unacceptable pressure fluctuations, making it often difficult to manufacture an exhaust gas receiver as one large hollow section. For this reason, the space inside the exhaust gas receiver is divided into compartments with orifices inside that restrict the flow between the compartments by a partition wall. Thus, the exhaust gas from the farthest cylinder must pass through multiple orifices before reaching the turbocharger, while the exhaust gas from the nearest cylinder does not need to pass through the orifice, The pressure at the distal end of the gas receiver is much higher than the pressure at the proximal end of the exhaust gas receiver. Distant cylinders with higher back pressure will experience higher thermal loads than cylinders near the turbocharger, and problems arise due to uneven distribution of back pressure to the cylinders. In order to avoid thermal damage to the cylinders that receive the highest thermal loads, it is necessary to reduce the overall thermal load on all cylinders. This means that the cylinders near the turbocharger are not operated at maximum capacity, thereby reducing the overall engine performance.

  Therefore, there is a need for a structure for making the pressure in the elongated exhaust gas receiver uniform.

  In this context, the present invention aims to provide an elongated exhaust gas receiver that at least partially meets the above-mentioned needs.

  This object is achieved by providing an elongated exhaust gas receiver for a large two-cycle diesel engine, said exhaust gas receiver being longitudinally divided into proximal and distal compartments, and in some embodiments one or more The exhaust gas receiver is provided with a plurality of exhaust gas inlets distributed in the longitudinal direction of the exhaust gas receiver, and the exhaust gas receiver extends along a part of the longitudinal direction of the exhaust gas receiver. A pressure distribution pipe extending from one of the longitudinal ends of the exhaust gas receiver, the pressure distribution pipe of a turbocharger disposed near one of the longitudinal ends An exhaust port opened to connect to the intake opening is provided, and the pressure distribution pipe connects the exhaust port to at least two of the compartments.

  By providing a line that equalizes the pressure along the exhaust gas receiver, the difference in back pressure sensed by the individual cylinders is substantially uniform. Thus, the thermal load on the cylinders is more evenly distributed, so that all the cylinders of the engine can be operated at approximately the maximum load level, thereby improving the overall performance of the engine.

  It is preferable that the pressure distribution pipe extends from the exhaust port to the distal section or the intermediate section along the exhaust gas receiver.

  The pressure distribution pipe may include a branch that connects to the proximal or intermediate compartment, or both the proximal and intermediate compartments.

  The exhaust gas receiver can comprise at least one intermediate compartment disposed between the proximal compartment and the distal compartment. In this case, the pressure distribution pipe comprises at least one further branch connecting to the intermediate compartment.

  The portion of the pressure distribution pipe that extends from the exhaust port to the first branch has the largest flow area, while the flow area of the portion of the pressure distribution pipe that leads to the end of the pressure distribution pipe is: It is preferred that it gradually decreases after each branch.

  The exhaust gas receiver can have one housing part divided into a plurality of compartments or a plurality of housing parts each including one or more compartments.

  The pressure distribution pipe may be disposed along an elongated exhaust gas receiver and is supported by at least one rigid support and at least one flexible support, the at least one flexible support being the pressure distribution The pressure distribution pipe is mounted on the engine portion in order to compensate for the difference in thermal expansion between the engine portion and the pressure distribution pipe. Placed.

  The pressure distribution pipe is preferably fixed in the longitudinal direction by the rigid support.

  The housing of the exhaust gas receiver may comprise two or more interconnected housings arranged in series.

  Further objects, functions, advantages and characteristics of the exhaust gas receiver according to the invention will become apparent from the detailed description.

Detailed Description of the Preferred Embodiment

  In the following detailed part of the description, the invention will be described in more detail with reference to exemplary embodiments shown in the drawings.

  1 to 3 show a side view, a front view, and a top view, respectively, of an engine 1 according to a preferred embodiment of the present invention. The engine 1 is a crosshead type single-flow low-speed two-cycle crosshead diesel engine, which can be a ship propulsion system or a power plant prime mover. These engines typically have up to 14 in-line cylinders. The engine 1 is composed of a base plate 2 having a main bearing for the crankshaft 5 (only the flywheel 3 attached to the end of the crankshaft is shown).

  The base plate 2 can be formed integrally or can be divided into portions of an appropriate size according to the production equipment.

  The welding type A-shaped frame box 4 is placed on the base plate 2. On the exhaust side, the frame box 4 includes a safety valve for each cylinder, and on the camshaft side, the frame box 4 includes a large hinged door for each cylinder. A crosshead guide plate (not shown) is incorporated in the frame box 4.

  The cylinder frame 5 is placed on top of the frame box 4. A retaining bolt (not shown) connects the base plate 2, the frame box 4, and the cylinder frame 5, and holds the structure together.

  The cylinder frame 5 carries individual cylinders 6. In this embodiment, the number of cylinders is 12.

  The cylinder frame 5 forms a scavenging space together with the cylinder liner 6. The scavenging receiver 9 is fixed to the cylinder frame 5 with bolts.

  Pistons (not shown) are received inside each cylinder liner 6. A piston rod (not shown) connects the lower part of the piston to the upper part of the crosshead (not shown). The cylinder liner 6 is carried by the cylinder frame 5.

  A turbocharger 10 is attached to the rear end of the engine. The cylinder is a single flow type and has a scavenging port (not shown) located in the air box, from which a scavenging receiver 9 is provided, and the scavenging is pressurized by the turbocharger 10.

  Intake into the turbocharger 10 is performed directly from the engine room via an intake silencer (not shown) of the turbocharger. The air is guided from the turbocharger 10 to the scavenging port of the cylinder 6 through the air cooler 11 and the scavenging receiver 9.

  The engine includes an electric auxiliary scavenging blower 13. The auxiliary blower assists the turbo compressor at low and medium load conditions.

  An exhaust valve (not shown) is attached to the upper center of the cylinder in the cylinder cover 14. After the expansion stroke, the exhaust valve opens before the piston of the engine descends and passes the scavenging port, and the combustion gas in the combustion chamber above the piston flows into the exhaust receiver 16 through the opening of the exhaust passage 15 (FIG. 2). This reduces the pressure in the combustion chamber. The exhaust valve closes again while the piston moves upward.

  The exhaust gas receiver 16 comprises a first housing part 17 and a second housing part arranged in series so as to form one elongated exhaust gas receiver. The exhaust gas receiver 16 is divided into two housing parts to compensate for dimensional changes in the housing of the exhaust gas receiver 16 caused by thermal expansion. Another reason for dividing the housing of the exhaust gas receiver into two or more parts is due to the maximum dimensions allowed by the production equipment.

  The interior of housing part 17 forms the distal compartment and the interior of housing 18 forms the proximal compartment.

  Both housing parts 17 and 18 of the exhaust gas receiver 16 are covered with a thick layer of insulation 20. Both housing parts 17 and 18 are supported by a rigid support 22 in the middle of their longitudinal direction. A plurality of flexible supports 23 are arranged on both sides of the rigid support 22 along the housing parts 17 and 18. The flexible support 23 is formed by a plate that allows the longitudinal movement of the exhaust gas receiver 16 necessary to compensate for the thermal expansion of the large housing parts 17 and 18.

  Each of the 12 cylinders of the engine 1 is connected to an intake port 24 of an exhaust gas receiver 16 by an exhaust passage 15.

  The cylinders 1 to 6 open toward the housing part 17, and the cylinders 7 to 12 open toward the housing part 18 through the intake port 24 of the exhaust gas receiver.

  The pressure distribution pipe 19 is disposed along the exhaust gas receiver 16. A first portion of the pressure distribution pipe 19 is a curved portion 25. The straight portion 26 of the pressure distribution pipe 19 extends along the housing part 18. At the end of the straight line portion 26, the branch 27 of the pressure distribution pipe 19 connects the inside of the pressure distribution pipe 19 to the inside of the housing part 18. Thereafter, the pressure distribution pipe is narrowed, and the second curved portion 28 connects the inside of the pressure distribution pipe 19 to the inside of the housing part 20.

  The pressure distribution circuit 19 can be provided with an orifice in a plate-like member 29 arranged in the longitudinal direction which serves to reduce pressure fluctuations.

  As with the housing parts 17 and 18, the pressure distribution pipe 19 is covered with a thick layer of insulation 20.

  The flow area of the portions 26 and 25 of the pressure distribution pipe 19 is larger than the flow area of the portion 28 of the pressure distribution pipe 19. The reason for the larger flow area is that the portions 26 and 25 of the pressure distribution pipe 19 carry a large amount of gas received in the exhaust gas receiver 16 to the inlet of the turbocharger, while the portion 28 of the pressure distribution pipe 19 is This is because the exhaust gas received by the housing part 17 is only transported.

  The resistance of the exhaust gas moving from the housing part 17 and the housing part 18 becomes uniform due to the difference in the flow area of the pressure distribution pipe 19. Thus, the thermal load on the cylinders is distributed substantially equally, so that all cylinders can be operated at nearly maximum load without overloading the individual cylinders.

  The exhaust gas receiver 16 can comprise a further housing part (not shown) arranged between the housing part 17 and the housing part 18. An intermediate section is formed by the interior of the further housing part. In one such embodiment (not shown), the pressure distribution pipe 19 includes a second branch connecting the interior of the pressure distribution pipe to the interior of the intermediate compartment. In one such embodiment, the pressure section of the delivery line has three different flow regions. The flow area is minimal in the portion of the pressure distribution pipe that transports only the exhaust gas from the distal section. The next smaller flow region is the portion of the pressure distribution compartment that transports exhaust gases from both the distal and intermediate compartments. The largest flow area is the portion of the pressure distribution pipe that transports the exhaust gas from all three compartments. Additional intermediate compartments can be added, and branch and staged flow regions are added to the pressure distribution piping for each added intermediate compartment (not shown).

  The pressure distribution pipe 19 may not be disposed along the exhaust gas receiver. Instead, for example, it can be arranged along the top of the exhaust gas receiver 16 (a gas receiver not shown).

  4 and 5 show another embodiment of an exhaust gas receiver according to the present invention. This embodiment is basically the same as that described above except that the turbocharger 10 is not necessarily placed behind the engine, and instead the exhaust near the rear of the engine 1 is placed along the gas receiver 16. Same as the embodiment. This embodiment is particularly advantageous in situations where the total length of the engine 1 has to be shortened (this may be required especially for the type of ship where the available engine room length is limited). It is. By moving the turbocharger 10 from the rear of the engine along the exhaust gas receiver 16 in the vicinity of the rear of the engine, the overall length of the engine 1 is reduced when compared with the above-described embodiment.

  The term “comprising”, used in the claims, does not exclude other elements or steps. The term “a” or “an” as used in the claims does not exclude a plurality.

  Although the present invention has been described in detail for purposes of illustration, it is to be understood that such details are merely for that purpose and that one skilled in the art can make changes without departing from the scope of the invention.

2 shows a long side view of a large two-cycle engine according to an embodiment of the present invention. Fig. 2 shows a front end portion of the engine shown in Fig. 1. 2 shows the upper part of the engine shown in FIG. 3 shows a long side view of a large two-cycle engine according to another embodiment of the present invention. Fig. 5 shows a front end portion of the engine shown in Fig. 4.

Claims (9)

An elongated exhaust gas receiver (16) for a large two-cycle diesel engine (1),
The exhaust gas receiver (16), in the longitudinal direction, either divided into proximal section and a distal section, or, proximal section, divided into distal compartment and one or more intermediate compartments,
The exhaust gas receiver (16) is provided with a plurality of exhaust gas inlets (24) distributed in the longitudinal direction thereof,
The exhaust gas receiver (16) comprises a pressure distribution pipe (19) extending from one of the longitudinal ends of the exhaust gas receiver along a part of the longitudinal direction of the exhaust gas receiver,
The pressure distribution pipe (19) has an exhaust opening that opens to connect to an intake opening of a turbocharger (10) disposed near one of the longitudinal ends,
The pressure distribution pipe (19) is an exhaust gas receiver that connects the exhaust port to at least two of the compartments.   The exhaust gas receiver according to claim 1, wherein the pressure distribution pipe extends from the exhaust port to the distal section or the intermediate section along the exhaust gas receiver.   The exhaust gas receiver according to claim 2, wherein the pressure distribution pipe (19) comprises a branch (27) connected to the proximal or intermediate compartment, or both the proximal and intermediate compartments. The exhaust gas receiver (16) comprises at least one intermediate compartment disposed between the proximal compartment and the distal compartment;
The exhaust gas receiver according to claim 3, wherein the pressure distribution pipe (19) comprises at least one further branch connected to the intermediate compartment.   The part of the pressure distribution pipe (25, 26) extending from the exhaust port to the first branch (27) has the largest flow area, while leading to the end of the pressure distribution pipe (19). 5. The exhaust gas receiver according to claim 4, wherein the flow area of the pressure distribution pipe part (28) gradually decreases after each branch.   The exhaust according to claim 1, wherein the exhaust gas receiver (16) has one housing part divided into a plurality of compartments or a plurality of housing parts (17, 18) each comprising one or more compartments. Gas receiver.   The pressure distribution pipe (19) is disposed along the elongated exhaust gas receiver (16) and supported by at least one rigid support (22) and at least one flexible support (23), The at least one flexible support is configured such that the positional relationship between the pressure distribution pipe (19) and the engine part can be shifted in the longitudinal direction, and the difference in thermal expansion between the engine part and the pressure distribution pipe The exhaust gas receiver according to claim 1, wherein the pressure distribution pipe is placed on the engine portion.   The exhaust gas receiver according to claim 7, wherein the pressure distribution pipe (19) is fixed in the longitudinal direction by the rigid support (22).   The exhaust gas receiver according to claim 1, wherein the housing of the exhaust gas receiver (16) comprises two or more housings (17, 18) arranged in series.